The "Scanner" class
*******************

A "Scanner" object is used to scan for LE devices which are
broadcasting advertising data. In most situations this will give a set
of devices which are available for connection. (Note, however, that
Bluetooth LE devices may accept connections without broadcasting
advertising data, or may broadcast advertising data but may not accept
connections).


Constructor
===========

Scanner([index=0])

   Creates and initialises a new scanner object. *index* identifies
   the Bluetooth interface to use (where 0 is **/dev/hci0** etc).
   Scanning does not start until the *start()* or *scan()* methods are
   called - see below for details.


Instance Methods
================

withDelegate(delegate)

   Stores a reference to a *delegate* object, which receives callbacks
   when broadcasts from devices are received. See the documentation
   for "DefaultDelegate" for details.

scan([timeout = 10])

   Scans for devices for the given *timeout* in seconds. During this
   period, callbacks to the *delegate* object will be called. When the
   timeout ends, scanning will stop and the method will return a list
   (or a *view* on Python 3.x) of "ScanEntry" objects for all devices
   discovered during that time.

   *scan()* is equivalent to calling the *clear()*, *start()*,
   *process()* and *stop()* methods in order.

clear()

   Clears the current set of discovered devices.

start()

   Enables reception of advertising broadcasts from peripherals.
   Should be called before calling *process()*.

process([timeout = 10])

   Waits for advertising broadcasts and calls the *delegate* object
   when they are received. Returns after the given *timeout* period in
   seconds. This may be called multiple times (between calls to
   *start()* and *stop()* ).

stop()

   Disables reception of advertising broadcasts. Should be called
   after *process()* has returned.

getDevices()

   Returns a list (a *view* on Python 3.x) of "ScanEntry" objects for
   all devices which have been discovered (since the last *clear()*
   call).


Sample code
===========

Basic code to run a LE device scan follows this example:

   from bluepy.btle import Scanner, DefaultDelegate

   class ScanDelegate(DefaultDelegate):
       def __init__(self):
           DefaultDelegate.__init__(self)

       def handleDiscovery(self, dev, isNewDev, isNewData):
           if isNewDev:
               print "Discovered device", dev.addr
           elif isNewData:
               print "Received new data from", dev.addr

   scanner = Scanner().withDelegate(ScanDelegate())
   devices = scanner.scan(10.0)

   for dev in devices:
       print "Device %s (%s), RSSI=%d dB" % (dev.addr, dev.addrType, dev.rssi)
       for (adtype, desc, value) in dev.getScanData():
           print "  %s = %s" % (desc, value)

NOTE that LE scanning must be run as root.

See the documentation for "ScanEntry" for the information available
via the *dev* parameter passed to the delegate.
